Hydraulic transmission for fabric-treating machines



Sept. 1, 1970 c, E, KURTZ 3,526,197

HYDRAULIC TRANSMISSION FOR FABRIC-TREATING MACHINES Filed June 24, 1968 4 Sheets-Sheet l 4 m H E;

f vo -V Q \NVENTOQ CUPT/S E. K0972 ATTORNEY p 1, 7 c. E. KURTZ 3,526,107

HYDRAULIC TRANSMISSION FOR FABRIC-TREATING MACHINES Filed June 24, 1968 4 Sheets-Sheet 2 C. E. KURTZ Sept. 1, 1970 HYDRAULIC TRANSMISSION FOR FABRIC-TREATING MACHINES 4 Sheets-Sheet 3 Filed June 24, 1968 Sept. 1, 1970 c, u -rz 3,526,107

HYDRAULIC TRANSMISSION FOR FABRIC-TREATING MACHINES Filed June 24, 1968 4 Sheets-Sheet 4 SPIN 3,526,107 HYDRAULIC TRANSMISSION FOR FABRIC- TREATING MACHINES Curtis E. Kurtz, Arlington Heights, 111., assignor to Borg- Warner Corporation, Chicago, Ill., a corporation of Delaware Filed June 24, 1968, Ser. No. 739,303 Int. Cl. D06f 23/04 US. Cl. 6823.7 20 Claims ABSTRACT OF THE DISCLOSURE A hydraulic transmission for operating an agitator for a fabric-washing operation and rotating a fabric container for a spin-extract operation and having a pump comprising a pumping element and a housing therefor, the pumping element being rotatable to supply washing fluid in the container to a vane-type hydraulic motor having a vane fixed to the container and a vane housing connected to the pump housing and to the agitator, the pump providing fluid under pressure reacting against the vane to provide movement of the housings to operate the agitator, the container being held against rotation during agitator operation and releasable to effect hydraulic coupling of the pump housing and pumping element to rotate the vane and its housing and thereby the container.

SUMMARY OF THE INVENTION This invention relates to a hydraulic transmission for fabric-treating machines.

An object of the invention is to provide an improved hydraulic transmission for fabric-treating machines having a rotatable fabric container and an oscillatable agitator in the container, and in which a hydraulic motor is operative to oscillate the agitator and is controllable to rotate the container.

Another object of the invention is to provide a hydraulic transmission for fabric-treating machines having an oscillatable agitator, a rotatable container, and a brake for the container, a hydraulic motor and a pump of the transmission being mounted in the agitator and cooperative to oscillate the agitator and, upon release of the brake, to rotate the container.

Another object of the invention is to provide a hydraulic transmission for fabric-treating machines having an oscillatable agitator and a rotatable container, and a brake for the container, the transmission having a pump with a pumping element and a housing therefor, a hydraulic motor having relatively movable parts respectively fixed to the container and to the pump housing and agitator to oscillate the agitator, and the pumping element and pump housing being hydraulically coupled to rotate the hydraulic motor and thereby the container when the brake is released.

Another object of the invention is to provide an improved hydraulic transmission for fabric-treating machines having an oscillatable agitator in a fabric container, the transmission having a vane-type hydraulic motor with its vane connected to the container and a vane housing connected to the agitator and operative to oscillate the agitator, and a pump having a pumping element and a housing therefor and connected to the vane housing, the pump providing fluid under pressure reacting against the vane to provide oscillating movement of the housings and agitator.

Another object of the invention is to provide a hydraulic transmission for fabric-treating machines having a cleaning fluid container, and an oscillatable agitator in the container, and in which a hydraulic motor operates to oscillate the agitator under the control of valving; and a United States Patent Office 3,526,107 Patented Sept. 1, 1970 pump circulates cleaning fluid from the container to and through passages connecting the pump, motor and valving and into the container to continually flush the passages during oscillation of the agitator.

Further objects and advantages of the invention will become apparent from the following description with reference to the accompanying drawings, the features of novelty characterizing the invention being pointed out particularly in the claims annexed to and forming part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 illustrates a fabric-treating machine embodying ing a preferred form of the hydraulic transmission of the present invention;

FIG. 2 is a vertical sectional view of the transmission and showing a pump, vane motor, and control valving, said section being taken on line 22 of FIG. 3;

FIG. 3 is a horizontal view of the vane motor and the valving of the transmission, taken on line 3-3 of FIG. 2;

FIGS. 4 and 5 are vertical sectional views of the vane motor housing, taken on lines 2-2 and 55, respectively, of FIG. 3;

FIG. 6 is a top view of the pump cover;

FIG. 7 is a top view of the bottom plate of the pump;

FIG. 8 is a top view of the upper plate of the vane motor;

FIG. 9 is a top view of the lower plate of the vane motor;

FIG. 10 is atop view of the transmission bottom plate;

FIG. 11 is a top view of the vane of the vane motor;

FIG. 12 is a bottom view of the vane of the vane motor; and

FIG. 13 is a schematic view of the hydraulic transmission.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a preferred embodiment of my improved hydraulic transmission 10 is shown in a fabrictreating machine in the form of a clothes-cleaning washer 11 having an oscillatable vaned agitator 12 to wash the clothes, and an imperforate clothes container or basket 13 positioned in a tub 14 and rotatable to extract washing liquid from the clothes.

Referring to FIGS. 1 and 2, the washer tub 14 has a bottom wall 16 with a depending centrally-located cylindrical support 17 for the basket 13, agitator 12 and the hydraulic transmission 10. More particularly, the lower end of the support 17 is provided with a radially inwardlydirected annular flange 19 engaging an annular resilient bushing 20 of rubber, or the like, receiving a ball bearing assembly 21. The outer race of the bearing assembly 21 is positioned on a support 22 substantially Z-shaped in cross-section with its lower inwardly extending flange 23 engaging the bottom of the outer race, and its top flange 24 overlying the top of the bushing. Mounted on and extending through the bearing assembly 21 is the transmission drive member or shaft 25. The shaft 25 extends through the hub 26 projecting downwardly from the basket bottom wall 27 and is journaled in the hub by roller bearings 28 supported by a radially inward ex tending flange 29 of the hub. The hub 26 of the basket is rotatable in a sleeve bearing 30 of the tub bottom wall 16 upon release of a brake band 31 of a brake 32 engaging the hub 26. A solenoid 33 has its armature 34 connected to the band 31 and actuatable by energizing an electric coil 35 to release the brake. An 0 ring 36 is received within an annular groove in the bearing 30 to prevent water in the tub flowing between the basket hub 26 and the bearing 30. An ring 37 is also located in a groove in the shaft 25 to prevent water in basket 13 flowing downwardly along the shaft and exteriorly of the tub.

The drive shaft 25 is rotated by a pulley 38 (FIG. 1) driven by a belt 39 engaging the pulley 38 and also a pulley 40 of a discharge pump 41 and a pulley 42 of an electric motor 43 mounted on the tub bottom wall 16. The pump 41 exhausts water from the tub through an opening in the tub bottom wall and to a drain exteriorly of the washer.

The improved hydraulic transmission comprises, in general, a positive displacement type pump 44 driven by the electric motor-drive shaft 25; a vane-type hydraulic motor 45 for oscillating the agitator; control valving 46 for the hydraulic motor 45; and the solenoid-operated brake 32 for the basket 13.

Referring to FIG. 2, the pump 44, hydraulic motor 45, and control valving 46 as shown positioned within the hollow bell-shaped dome 47 of the agitator body. The hydraulic fluid for operating the hydraulic transmission is provided by the fabric-cleaning fluid, such as water or perchloroethylene, in the basket flowing through circumferentially-spaced openings 48 in the agitator dome 47 into the sump 49 provided by the hollow interior of the dome. In FIGS. 2 and 13, the suction port of the pump is indicated at 50, the pump directing fluid under pressure to the valving 46 controlling flow of fluid to the hydraulic motor to oscillate the agitator and to discharge the fluid from the motor to the outlet ports 51 and 51a (FIGS. 3 and 13) of the valving and into the sump and basket. The sump 49 is illustrated for convenience in various places in the schematic view of FIG. 13, although in actual construction, one fluid sump 49 is provided into which all of the exhaust connections for various elements of the transmission exhaust pressure.

Referring now more particularly to the transmission, FIGS. 4-12 illustrate various structural components and FIGS. 1 and 2 illustrate their assembly, while FIG. 13 schematically identifies the components in their operative relation to each other and to the agitator, basket, and drive motor, and with particular reference to the fluid passages interconnecting the components in the performance of their functions in controlling oscillating movement of the agitator and rotation of the basket.

In general, and as shown in FIGS. 1, 2 and 3, the transmission structure comprises a unitary assembly adapted to be drivingly connected to the agitator and to the basket. Referring to FIG. 2, the transmission has top and bottom plates 52 and 53 (respectively shown in FIGS. 6 and confining the operating components of the transmission including the pump 44 having a housing 54, vane motor 45 having a housing 55 providing means defining a chamber receiving fluid under pressure from the pump, and control valving 46 in the housing 55. A plurality of bolts of bolt and nut assemblies 56 extend through aligned openings in the top and bottom plates 52 and 53 and the housings 54 and 55 to connect the pump, vane motor and valving in an operative assembly. The bottom plate 53 extends radially outwardly of the housing 55 and engages a plurality of bosses 57 projecting downwardly of the dome 47 of the agitator and having threaded engagement with bolts 58 to secure the plate 53 to the agitator.

Referring to FIGS. 2, 6, 7 and 13, the pump 44 is a conventional positive displacement gerotor type having a pumping element provided by inner and outer rotors 59 and 60 rotatable in the housing 54, the inner rotor 59 being an externally toothed gear keyed to the drive shaft 25, and the outer rotor 60 being an internally toothed ring gear meshing with the gear 59 and engaging the inner surface of a cylindrical ring 61 of the housing 54. The housing 54 also includes the upper plate 52 and a lower plate 62 shown in detail in FIGS. 6 and 7 respectively.

The outer rotor 60 has its spaced teeth providing recesses 63 (FIG. 13) for receiving the teeth 64 on the inner rotor 59 so that, upon rotation of the rotors in a clockwise direction, during the agitate cycle, fluid will enter the inlet port 50 in plate 52 and the rotors will act on the fluid in the chambers between the teeth 64 of the inner rotor and the recesses 63 of the outer rotor to provide fluid under pressure to a port 84 in the lower plate 62.

The vane-type hydraulic motor 45 is shown structurally in FIGS. 2-5, 8, 9, ll, 12 and schematically in FIG. 13 and comprises the housing or body 55, defining with top and bottom fluid-passage plates 67 and 68, a fluid chamber in which is received a vane 69 fixed to the bottom wall 27 of the basket 13 and providing a stationary member of the motor during oscillation of the agitator. As seen in FIGS. 3, 4 and 5, the body 55 has a hollow portion 70 including a wall projecting radially inwardly into the chamber and with the vane 69 dividing the chamber into two portions 70a and 70b, an arcuately concave surface of the wall engaging the cylindrical side portion of the vane hub 69a to provide, with the vane, expansible and contractible fluid chamber portions 70a and 7011.

A feature of the invention is the hydraulic motor arrangement that provides for the vane housing 55 to reciprocate as fluid under pressure is admitted alternately into the chamber portions 70a and 70b to opposite sides of the vane 69 to oscillate the agitator during the washing cycle. As seen in FIG. 2, the vane extends outwardly from and is formed integral with a sleeve shaft 71 in which the shaft 25 is journaled and extends upwardly for driving connection, by a key as shown, to the pump inner rotor 59. The lower end of the shaft 71 is in screwthreaded engagement with a plate 72 secured to the bottom wall 27 of the basket 13 by bolt and nut assemblies 73. When the brake 32 holds the basket stationary, the vane is also held against rotation while the vane housing can reciprocate to oscillate the agitator. The vane has an arcuate tip conforming to the cylindrical interior surface 74 of the body 55 and, as shown in FIGS. 3 and 12, the tip is provided with a recess receiving a spring 75 and plunger 76, the spring actuating the plunger into engagement with the surface 74 to preclude fluid flow between the chamber portions 70a and 70b. It may be noted that the plates 62, 67, 68 and 53 contain various fluid ports and passages cooperating with ports and passages in the vane motor housing 55, the vane 69, and control valving 46 in a manner now to be described.

Referring to FIGS. 3, 11 and 12, the top surface of the hub 69a of vane 69 has an arcuate groove 80, and the bottom surface of the hub contains spaced arcuate grooves 81 and 82. When the vane moves to the limits of its travel in opposite directions, these grooves in the hub cooperate with passages in the plates 53, 62, 67, 68 to control the operation of a valve spool 83 of the valving 46 to direct fluid under pressure alternately to the chambers 70a and 70b to reciprocate the vane and pump housings and thereby oscillate the agitator.

Referring to FIG. 2, the plates 53, 62, 67 and 68 are shown in the transmission assembly. FIGS. 10, 7, 8 and 9 illustrate the plates 53, 62, 67 and 68 individually. In FIG. 2, plate 62 has its top surface contacting the lower surfaces of the pump housing and rotors, and its bottom surface contacts the top plate 67. The bottom surface of plate 67 engages the upper sides of the vane 69 and the vane and valve housing body 55 and also the upper surface of plate 53. The plates 62 and 67 have arcuate openings 84 and 85, respectively, aligned with each other and with a correspondingly arcuately-shaped chamber 86 of the housing 55 (FIG. 3) so that fluid under pressure, discharged from the pump, flows through openings 84 and 85 and into the chamber 86 and through control valving 46 selectively directing the fluid alternately to the expansible and contractible chambers 70a and 70b of the housing, the fluid reacting against one side and then the other side of the stationary vane to reciprocate the connected pump and hydraulic motor housings and thereby the agitator relative to the vane.

Referring to FIG. 3, the vane motor housing 55 contains means controlling flow of fluid from the pump to the chambers 70a and 70b of housing 55 in the form of the agitator control control valving 46 including the valve spool 83 reciprocable in a tangential bore 87 in the housing, under the influence of fluid under pressure controlled by the vane 69, to direct fluid under pressure alternately into the chambers 70a or 70b, to reciprocate the pump and hydraulic motor housings 54 and 55 and the agitator. More particularly, the spool 83 is provided with lands 88, 89 and 90, the lands 88 and 89 being separated by a groove 91 and the lands 89 and 90 being separated by a groove 92. The ends of the bore are provided with plugs 93 and 94. The spool is shiftable by fluid under pressure supplied successively to opposite ends of the spool.

Referring to FIGS. 3 and 13, the area of the housing 55, providing the valve bore 87, includes ports 95, 96, 97, 98, 99, 100 and 101. Fluid passages 102 and 103 are respectively connected to chambers 70a"and 70b and to ports 97 and 99. Conduits 51 and 51a are connected to ports 96 and 100 respectively, and are exhaust passages connected to the sump 49. Conduits -6 and 107 are connected to ports 95 and 101, respectively, to provide fluid under pressure alternately to opposite ends of the spool to shift the spool. Conduits 108 and 109 are also in fluid communication with ports 95 and 101, respectively. The conduit 108 serves to exhaust fluid between spool land 90 and plug 94 to the sump when fluid under pressure is admitted to port 101 between spool land 88 and plug 93 to move the spool in one direction. The conduit 109 serves to exhaust fluid between spool land 88 and plug 93 to the sump when fluid under pressure is admitted to port 95 between spool land 90 and plug 94 to move the spool in the other direction.

To control the movement of the valve spool by the vane 69 and thereby movement of the pump and hydraulic motor housings relative to the vane, the plate 62 (FIG. 7) has its lower surface provided with the grooves 106 and 107, and also two grooves 110 and 111 connected to the discharge side of the pump so that fluid under pressure is directed to these grooves 110 and 111 during pump operation. The plate 67 (FIG. 8) has openings 112, 113, 114 and 115 therein, the openings 112 and 113 receiving fluid under pressure from grooves 110 and 111 of plate 44 and openings 114 and 115 being respectively positioned beneath the radially inner ends of the grooves 107 and 106. Accordingly, rotation of the coupled hydraulic motor and pump housings about the vane (FIG. 13) in a counterclockwise direction causes the groove 80 of the vane to bridge the fluid pressure-charged opening 112 and opening 114 to direct fluid to groove 106 and to port 95 of the valve to move the spool 83 to the right. Simultaneously, the vane will position its groove 81 to bridge openings 117 and 118 in plate 68 so that fluid can be discharged from the valve through port 101, passage 109, openings 117 and 118 and 119 to the sump. When the hydraulic motor and pump housings rotate about the vane (FIG. 13) in a clockwise direction, the vane will position its groove 80 to bridge the fluid pressure-charged openings 113 and 115 to direct fluid to groove 107 to port 101 of the valve to move the spool 83 to the left. At this time, the vane has positioned its groove 82 to bridge openings 116 and 118 and 119 to the sump.

It will be apparent that, when the brake 32 is effective to prevent rotation of the basket and the vane of the vane motor, oscillation of the agitator is provided by directing fluid under pressure from the pump alternately to the hydraulic motor chamber portions 70a and 70b to cause reciprocating movement of the coupled hydraulic motor and pump housings, connected to the agitator, to oscillate the agitator. When the valve spool 83 is in the FIG. 13 position, fluid under pressure has entered port 98 of the valve and between lands 88 and 89 of the valve, port 99, passage 103 and into chamber 70b to cause movement of the housings in a counterclockwise direction. When sufficient rotation has occurred, the vane controls movement of the valve spool, as previously described, toward the right in FIG. 13 by directing fluid under pressure from the pump to the left end of the spool, so that the spool is positioned to permit fluid entering port 98, to flow between the lands 89 and of the spool, port 97 and groove 102 into chamber 70a to rotate the housings in a clockwise direction, fluid exhausting from chamber 70b flowing through passage 103, port 99 to port and through passage 51a to sump 49.

Referring to FIG. 13, an electrical control arrangement is provided for selecting a WASH cycle or opera tion or a SPIN cycle or operation of the clothes-cleaning machine. More particularly, electric conductors 121 and 122 interconnect a source of power 123 with motor 43; the conductor 121 being a ground conductor. A cycle selector switch 124 is connected to the motor by a conductor 125. The switch 124 is schematically illustrated in a simplified form although an automatic sequence of washing, rinsing, and spinning cycles could be provided by timers well known in the art. Conductors 126 and 127 connect the brake solenoid 33 to the switch 124 so that completion of a circuit to energize the winding 35 of the solenoid 33 of the brake will be effective to release the brake band 31 from engagement with the hub 26 of the basket 13 to permit rotation of the basket for a SPIN operation.

Upon release of the brake 33, the pump rotors and housing will be hydraulically coupled to be rotated as a unit by the motor 43, the pump reaction and the mechani cal frictional engagement of the pump components causing rotation of the hydraulic motor housing and vane and thereby the basket at a desired speed to extract the cleaning fluid from the clothes in the basket. During the initial spin period, the pump flows near its full capacity with a high reaction torque for high acceleration. As the capacity of the pump decreases and the spin relation between the pump housing and rotors approaches zero, the flow and reaction torque decreases, and the internal pump components friction causes the transmission and thereby the basket to attain the desired spin speed approximating the speed of rotation of the drive shaft 25.

It will be apparent from the description of the hydraulic transmission of the present invention that an important inventive feature resides in the provision of the hydraulic vane motor having its vane fixed to the clothes container of a fabric-cleaning machine and having its vane housing connected to rotate with the pump housing so that the pump rotors operate to provide fluid under pressure to oscillate the vane housing and thereby the agitator, the trans-mission being provided with a brake preventing movement of the vane and rotation of the basket during agitator oscillation but being releasable to permit rotation of the basket for a SPIN operation by the hydraulic coupling of the pump components. Another important feature of the transmission is that it can be accommodated within the interior of the agitator to provide a compact space-saving arrangement. A further valuable feature is the location and disposition of the transmission hydraulic motor, pump and valving to provide for the use of the fabric-cleaning fluid as an inexpensive operating fluid of the transmission and its circulation through the pump, motor and valving is effective to continually flush the passages to insure freedom from dirt, lint and other foreign matter, during oscillation of the agitator.

Although a pump of the gerotor or gear type has been shown to illustrate the present invention, obviously other positive displacement or expansible chamber type pumps, including vane pumps, can also function satisfactorily and be used in practicing the invention.

While I have shown and described a preferred embodiment of the invention, it will be understood that the inven- 7 tion is not limited thereto since the invention may be embodied within the scope of the appended claims.

What is claimed is:

1. In a fabric-treating machine, a container; an agitator in said container; a motor having a rotatable drive member; a hydraulic pump including a pumping element connected to said drive member, and a housing for said pumping element; a hydraulic motor having movable means defining a chamber for receiving fluid under pressure from said pump and connected to said agitator and said pump housing, and a stationary member in said chamber; and means controlling flow of fluid to said chamber from said pump to actuate said movable means and thereby said agitator by fluid reacting against said stationary member.

2. In a fabric-treating machine as defined in claim 1 wherein said pump is of the positive displacement type.

3. In a fabric-treating machine as defined in claim 1 wherein said pump is of the gerotor type, the pumping element comprising an externally toothed gear connected to the drive member, and an internally toothed ring gear rotatable in the pump housing and meshing with the externally toothed gear.

4. In a fabric-treating machine as defined in claim 1 wherein said hydraulic pump, said hydraulic motor, and said fluid-flow controlling means are positioned within said agitator.

5. In a fabric-treating machine as defined in claim 1 wherein said stationary member divides said chamber into expansible and contractable portions, and said fluid-flow controlling means is valving operative to alternately direct fluid under pressure from said pump into one chamber portion while exhausting fluid from the other chamber portion.

6. In a fabric-treating machine as defined in claim 5 including means for operating said valving and controlled by said movable means.

7. In a fabric-treating machine as defined in claim 5 wherein said valving includes valve means having a valve body with passages connected to said fluid chamber and to pressure and exhaust ports, and a valve member in said body and disposed between said pressure and exhaust ports and shiftable to direct fluid to and from said chamber; and control means operable by said movable means to open and close said pressure and exhaust ports to shift said valve member.

8. In a fabric-treating machine as defined in claim 5 wherein said hydraulic pump, hydraulic motor, and valving are positioned in said container and provided with connecting passages including a pump inlet suction passage communicating with fluid in said container, and a hydraulic motor outlet passage controlled by said valving to exhaust fluid into said container.

9. In a fabric-treating machine as defined in claim 8 wherein said hydraulic pump, hydraulic motor, and

tator in said basket, the drive arrangement comprising a pump having a pumping element and a housing therefor; a hydraulic motor having a vane and a housing therefor, said motor and pump housings being connected to and movable with said agitator and said vane being connected to and rotatable with said basket; a brake for preventing rotation of said basket and said vane; an electric motor having a drive member connected to said pumping element; means for controlling operation of said hydraulic motor to actuate said housings and thereby said agitator; and means for operating said brake to release said brake and thereby hydraulically coupling said pump housing with said pumping element to rotate said basket.

13. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 12 wherein said pump is of the positive displacement type.

14. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 12 wherein said pump is of the gerotor type, the pumping element comprising an externally toothed gear connected to the drive member, and an internally toothed ring gear, said ring gear being rotatable in the pump housing and meshing with the externally toothed gear.

15. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 12 wherein said hydraulic pump, said hydraulic motor, and said controlling means are mounted in said agitator.

16. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 12 wherein said hydraulic motor housing and vane provides expansible and contractable chambers, and said controlling means is valving operative to alternately direct fluid under pressure from said pump into said chambers and to exhaust fluid from said chambers.

17. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 16 including means for operating said valving and controlled by movement of said hydraulic motor housing.

18. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 16 including valve means of said vane and vane housing operative to direct fluid to control operation of said valving.

19. In a hydraulic drive arrangement for a fabriccleaning machine as defined in claim 16 wherein said hydarulic pump, hydraulic motor, and valving are located in said container and provided with connecting passages including an inlet suction passage in said pump housing and communicating with fluid in said container, and an outlet passage in said hydraulic motor housing and controlled by said valving to exhaust fluid into said container.

20. In a drive arrangement as defined in claim 16 wherein said hydraulic pump, hydraulic motor, and valving are mounted in said agitator.

References Cited UNITED STATES PATENTS 2,574,418 11/1951 Rubano 6053 2,592,597 4/1952 Pengelly 6823.5 2,996,908 7/1961 De Zarate 6823 3,242,703 3/1966 Brundage 6823.7 3,366,015 1/1968 Haas et al -1 68-23 XR 3,388,569 6/1968 Kurtz 6823.7

ROBERT L. BLEUTGE, Primary Examiner US. Cl. X.R. 60-53 Patent No. 3,526,107 September 1, 1970 Curtis E. Kurtz ears in the above identified It is certified that error app eby corrected as patent and that said Letters Patent are her shown below:

"contractable" should read contractible should read provide line 31,

line 45, "hydrulic" Column 7, line 30,

Column 8, line 30, "provides "contractable" should read contractible should read hydraulic Signed and sealed this 16th day of March 1971.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

